For electric wiring in the inside of a car, in particular, electric wiring of equipment that is easily affected by noise or easily generates noise, a shielded electric wire provided with an electric shielding layer around an internal conductor executing transmission of a signal is used.
A shielded electric wire available on the market generally consists of an internal conductor executing transmission of a signal, an insulation layer enclosing around the internal conductor, an external conductor functioning as a shielding layer enclosing the outer circumference of the insulation layer, and an insulation outer sheath covering the outer circumference of the external conductor. In general, the insulation layer and the insulation outer sheath are formed by extrusion molding.
The shielded electric wire available on the market is expensive compared to a common coated conductive wire having no shielding layer. Since the shielded electric wire has high bending strength, availability of arrangement thereof is inferior.
Instead of the expensive shielded electric wire available on the market, manufacturers, which have manufactured wire harness to be in a vehicle and others, have introduced a shielded electric wire wrapped with metal foil, in which a drain wire that is a naked conductor is provided along length of a general coated conductive wire, and a metal foil member is wrapped around the coated conductive wire and the drain wire, so that the wrapped metal foil member is utilized as a shielding layer (for example, refer to Patent Literatures 1 and 2).
In the shielded electric wire wrapped with metal foil, for example, a metal foil film, in which a metal foil layer is formed on one side surface of an insulation film, is used as the metal foil member. The metal foil film is wrapped around the outer circumference of the coated conductive wire and the drain wire while directing the metal foil layer toward the interior side, so that the metal foil layer is in contact with the drain wire, and the metal foil layer and the drain wire are in the electrically connected state. By grounding an end of the drain wire extending from an end of the coated conductive wire, the shielding layer can be easily grounded.
Since the shielded electric wire wrapped with metal foil has high flexibility, compared to the shielded electric wire available on the market, the availability of arrangement thereof can be improved. Since the number of core wires can be easily changed, the shielded electric wire wrapped with metal foil is suitable for shielding wiring of wire harness to be mounted in a vehicle, in which the number of core wires to be contained varies depending on equipment to be mounted in the vehicle.